Is this a standard part, or is it only required to buy the finished products from other factories, or do you want to design and size it yourself?
Standard parts can be purchased. It is better to bring the old parts with them or to provide the corresponding machine tools
According to the specifications of the tools you have used before
General milling machine seems to be a root screw, if the NC milling machine is pneumatic or hydraulic broach device. CNC accessories sold, the package should also have, but very expensive. Not interchangeable by different manufacturers. Structurally simple steel ball with broach claws.
